I've now completed a stay of four nights at the Fontecruz. My review is likely somewhere between the 1st two posters. One, I cannot say enough about the staff - they were accommodating, helpful and did their best to handle any questions and issues - though I speak no Portuguese and little Spanish. Everyone from the bartender to the Manager on duty and extremely attentive front desk staff was excellent.
Internet - I had issue at various times while staying. I had to move completely due to lack of connect-ability (don't stay on Floor 6), but the MGR on duty was empathetic and helpful - even giving me a slightly better room. At times, the internet was great, other times I could not connect at all; and sometimes just really slow to the point that you gave up getting anything done. This is an area this hotel needs to improve on.
Decor - unusual, artsy, dark, film noir - without good daylight (depends on the side of hotle you are one) the rooms are very dark considering the CFL lighting and color schemes. That said, the entire hotel is dark - but it is clearly the design they are going for, so can't knock them totally. Just be aware, if you need a lot of light to see, this probably is not the right Marriott for you.
Location - absolutely perfect. Waking distance to all the key neighborhoods and insanely close subway station to assist if you don't feel like walking or if you are exploring outside Lisbon without a car. It's even the best way to transfer from the airport.
Amenities - lack of pool, fitness room and room service/full meal service all True - so if you NEED these items and can;t find a workaround, not for you.
MR Platinum - very decent breakfast comped each morning for wife & I - really no complaints. Coffee and offerings may be different than what you are accustomed to, but plenty to get by on.
PS- I have found tissues elusive in many European hotels. Also, limited charge sockets AND, as is common in European hotels, when you leave room, electric shuts down (without card in room slot) - this can complicate charging devices while out of room